// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2020 Google Inc. All rights reserved.
// http://code.google.com/p/ceres-solver/
//
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// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer.
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//   and/or other materials provided with the distribution.
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// Author: darius.rueckert@fau.de (Darius Rueckert)

#ifndef CERES_INTERNAL_CODEGEN_TEST_UTILS_H_
#define CERES_INTERNAL_CODEGEN_TEST_UTILS_H_

#include "ceres/internal/autodiff.h"
#include "ceres/random.h"
#include "ceres/sized_cost_function.h"
#include "test_util.h"

namespace ceres {
namespace internal {

// CodegenCostFunctions have both, an templated operator() and the Evaluate()
// function. The operator() is used during code generation and Evaluate() is
// used during execution.
//
// If we want to use the operator() during execution (with autodiff) this
// wrapper class here has to be used. Autodiff doesn't support functors that
// have an Evaluate() function.
//
// CostFunctionToFunctor hides the Evaluate() function, because it doesn't
// derive from CostFunction. Autodiff sees it as a simple functor and will use
// the operator() as expected.
template <typename CostFunction>
struct CostFunctionToFunctor {
  template <typename... _Args>
  CostFunctionToFunctor(_Args&&... __args)
      : cost_function(std::forward<_Args>(__args)...) {}

  template <typename... _Args>
  bool operator()(_Args&&... __args) const {
    return cost_function(std::forward<_Args>(__args)...);
  }

  CostFunction cost_function;
};

// Evaluate a cost function and return the residuals and jacobians.
// All parameters are set to 'value'.
std::pair<std::vector<double>, std::vector<double>> EvaluateCostFunction(
    CostFunction* cost_function, double value);

// Evaluates the two cost functions using the method above and then compares the
// result. The comparison uses GTEST expect macros so this function should be
// called from a test enviroment.
void CompareCostFunctions(CostFunction* cost_function1,
                          CostFunction* cost_function2,
                          double value,
                          double tol);

}  // namespace internal
}  // namespace ceres

#endif
